Telephone system and method for reliable emergency services calling

ABSTRACT

A method of routing a telephone call includes receiving an indication, at a handset device  112 , to initiate a telephone call. It is then determined, preferably by the handset device  112 , whether the telephone call is an emergency services telephone call. If the telephone call is not an emergency services telephone call, it is routed to a proxy server  134 . On the other hand, if the telephone call is an emergency services telephone call, it is routed to a local gateway  116  without first accessing the proxy server  134.

RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.10/157,371 filed May 29, 2002, which claims priority under 35 U.S.C. §119 based on U.S. Provisional Application No. 60/373,993, filed Apr. 19,2002, the entire disclosures of which are incorporated herein byreference.

FIELD OF THE INVENTION

This invention relates generally to communication systems and morespecifically to a telephone system and method for reliable emergencyservices calling.

BACKGROUND OF THE INVENTION

The proliferation of data transport networks, most notably the Internet,is causing a revolution in telephony and other forms of real-timecommunication. Businesses that have been accustomed to having telephonytraffic and data traffic separately supported over different systems andnetworks are now moving towards so-called “converged networks.” In thesenetworks, telephone voice traffic and other forms of real-time media areconverted into digital form and carried by a packet data network alongwith other forms of data. Now that the technologies are feasible tosupport converged networks, voice over data transport offers manyadvantages in terms of reduced capital and operating costs, resourceefficiency and flexibility.

To meet the demand for voice over data transport, service providers andnetwork equipment vendors are faced with the challenges of establishingnew protocols and standards, recognizing new business models,implementing new services, and designing new equipment in a way thatwould have been difficult to imagine twenty years ago. For example, anew generation of end user terminal devices are now replacing thetraditional telephones and even the more recent PBX phone sets. Thesenew sets, such as those offered by Cisco Systems Inc. and PingtelCorporation, may connect directly to a common packet data network, viaan Ethernet connection for example, and may feature large visualdisplays to enhance the richness of the user interface.

Even before such devices were developed, computers equipped with audioadapters and connected to the Internet have been able to conduct somerudimentary form of Internet telephony, although the quality wasunpredictable and often very poor. The emphasis now is upon adaptingInternet Protocol (IP) networks and other packet sport networks toprovide reliable toll-quality connections, easy call set-up and enhancedfeatures to supply full-featured telephony as well as other forms ofmedia transport. Some other types of media sessions enabled by suchtechniques may include video, high quality audio, multi-partyconferencing, messaging and collaborative applications.

Of course, as a business or residential communications subscriber beginsusing such voice-over-packet communications to replace conventionaltelephony, there will naturally be an expectation that the quality ofthe connections and the variety of services will be at least as good asin the former telephone network. People have grown accustomed to havinga telephone connection available whenever it is necessary. This isespecially true in the case of emergencies where having an availabletelephone line can be most critical.

SUMMARY OF THE INVENTION

Embodiments of the present invention relate to emergency servicesnotification. In voice-over-IP systems, for example, the ability toreach emergency services, such as by using the well known “9-1-1”dialing sequence, must be supported by a packet voice system. As with aconventional telephone system, the availability of emergency services byphone in a voice-over-IP system is expected to be robust to catastrophicevents, such as natural disasters or military attacks.

One preferred embodiment of the present invention relates to ensuringthat special services, such as emergency or “911” services, areavailable even when some elements and functions in the service-providingnetwork become unavailable. Such unavailability may be caused by damageto equipment, power outages, or damage to communications links, forexample, in the case of a natural disaster. Network unavailability mayalso be caused by increased demands for service as large numbers ofpeople attempt to place calls into and out of an affected area.

New voice-over-packet networks may require special measures to ensureavailability of emergency services, even when conventional services areimpacted. For example, where essentially all of the call processing androuting logic resides in the service providing network rather than acustomer premise, it may be necessary to provide for routing ofemergency calls even when the customer premise is disconnected from theservice-providing network. The preferred embodiment of the presentinvention provides for this capability.

In accordance with a preferred embodiment, the present inventionprovides for a customer premise with direct access to a network gatewaythat interfaces to a Class 5 end office switch in the public switchedtelephone network (PSTN). Each phone at the customer premise includes aprovisionable feature for detecting the dialing of an emergency numberand addressing the session setup request to the local network gatewayrather a proxy server residing in a service providing network. In thismanner, the customer premise phones may be provisioned to differentiateemergency calls and bypass the voice-over-packet core network entirely.The customer premise phones are thus no longer dependent upon thereaching the voice-over-packet network to enable emergency services.

In one aspect, the present invention provides a method of routing atelephone call originating at a local customer premise. A handset devicereceives an indication to initiate a telephone call. It is thendetermined, preferably by the handset device, whether the telephone callis an emergency services telephone call. If the telephone call is not anemergency services telephone call it is routed to a proxy server. On theother hand, if the telephone call is an emergency services telephonecall, it is routed to a local gateway without first accessing the proxyserver.

In one embodiment of the present invention, a dialing “string” at thephone may be freely mapped to any actual emergency number applicable tothe region where the phone is located. In other words, if a customerpremise is located in an area where “911” dialing is not supported,phones may be nevertheless provisioned such that dialing of “9-1-1”reaches the applicable 7- or 10-digit emergency telephone number for thearea.

Aspects of the present invention provide a number of advantages. Forexample, because emergency services telephone calls are not dependentupon the IP network, performance issues related to the network can beavoided. As an example, if a cut line isolates the local network fromthe proxy server, an emergency services telephone call can still becompleted.

BRIEF DESCRIPTION OF THE DRAWINGS

The features of the present invention will be more clearly understoodfrom consideration of the following descriptions in connection withaccompanying drawings in which:

FIG. 1 is a block diagram showing a telecommunications system; and

FIG. 2 is a block diagram of an exemplary telephone that can be utilizedwith the system.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

The making and use of the various embodiments are discussed below indetail. However, it should be appreciated that the present inventionprovides many applicable inventive concepts that can be embodied in awide variety of specific contexts. The specific embodiments discussedare merely illustrative of specific ways to make and use the invention,and do not limit the scope of the invention.

A preferred embodiment of the present invention will now be describedwith reference to the figures. FIG. 1 shows a preferred system 100 thatcan be modified to include aspects of the present invention.Telecommunications system 100 includes both customer premise portion 110and a service provider portion 120. The customer premise portion 110 istypically located at a customer site, i.e., the place where thetelephone service is provided. The customer location may be a singlebuilding, a campus of buildings, or other configurations depending uponthe particular user. In some cases, the customer premise portion 110could also include a number of remotely located facilities that utilizecommonly shared network resources. Typically the customer premiseportion 110 is outside the control of the telecommunications serviceprovider.

A telecommunications service provider typically operates the serviceprovider portion 120. The service provider portion 120 is typicallyconnected to many different customers and includes a telecommunicationsbackbone. The service provider network 120 can be national or eveninternational, having the ability to connect users globally. For thepurposes of this discussion, the description will focus on the portionof the network that interfaces with customer premise 110.

Referring to the customer premise portion 110, a number of telephones orhandsets 112 are provided. These handsets 112 are provided to allowusers at the customer premise 110 to communicate as is necessary intheir business or otherwise. Telephones 112 are preferably IPtelephones, that is, they communicate using Internet Protocol packets Atypical embodiment could use IP telephones such as those commerciallyavailable from Cisco Systems Inc. or Pingtel Corporation, as modified inaccordance with the descriptions provided here. In another embodiment,telephone 112 could comprise an analog telephone coupled to a converterthat generates the packets.

Each of the handsets 112 is coupled to a local area network (LAN) 114.LAN 114 can be configured in any manner that is appropriate to connect anumber of devices using a common protocol, such as Internet Protocol.LAN 114 can include a number of devices, such as routers, servers, andcomputers, besides those that are shown in the figure. In a typicalembodiment, the LAN 114 can connect many telephones.

One of the elements coupled to LAN 114 is local network gateway 116.This local gateway 116 could be on customer premises or it could be offcustomer premises. One of the purposes of local gateway 116 is toprovide connectivity to the public switched telephone network (PSTN) 130through an element such as Class 5 switch 122.

FIG. 1 also shows a router 118, which can be used to connect to theservice provider 120. Wile router 118 is shown as the only element thatconnects the local customer premise network 110 to the service providerIP network 126, it is understood that other paths may also exist. Thesepaths preferably use a packet-based protocol such as IP. An advantage ofhaving LAN 114 use the same protocol as the service provider 120 is thatthe local network will appear to have all the features of the serviceprovider network. This provides a cost effective way to provide a vastarray of services that might otherwise not be affordable to a small oreven medium sized customer.

The service provider IP network 126 includes a number of circuitelements such as routers, servers and other devices, only a few of whichare shown in the figure. For example, a router 124 is shown as anexample of an entry point of messages from LAN 114, e.g., through router118. It is understood that different paths of entry may be present andother elements that are not shown could be included in the path.

The IP network 126 couples different elements and services. For example,network gateway 128 provides a path to PSTN 130. In a typicalconfiguration, network gateway 128 is connected to a Class 3 switch. Asis known, Class 3 switches provide much of the backbone of the PSTN 130.Since the service provider 120 routes a large amount of traffic throughto the PSTN, it is cost effective to couple directly to a Class 3switch. Alternatively, a Class 4 or a Class 5 switch could replace Class3 switch 132. Also, it is understood that the service provider may havenumerous gateways 128 to the PSTN 130.

FIG. 1 also illustrates a proxy server 134. These devices provide thefiction of routing the telephone calls through the most efficient andcost-effective portions of the network. In a typical embodiment, theserver 134 would comprise a high power computer, such as amultiprocessor computer, coupled to a database storage system.

To understand some of the advantages of the present invention, it isuseful to first describe the operation of the network. To place atelephone call a user picks up a handset 112. Upon receipt of a dialtone, the user dials the telephone number. In other embodiments, thehandset 112 could be voice activated or be coupled through a keyboard ofa computer, as examples. These variations, as well as others, are allincluded within the scope of the present invention.

The handset 112 routes a setup message to the proxy server 134. Theproxy server 134 authenticates to very the person and includes routinginformation from which it looks up the dialed digits. For example, theproxy server 134 will determine if the phone number is a long distancenumber, is a local number, or is a PBX extension, as examples.

The system then routes the call as appropriate. For example, if the callis a long distance call, it could be routed to the PSTN through networkgateway 128 and Class 3 switch 132. If the dialed number is a localnumber, it might be routed through the network gateway 128 to completethat call. It might be less expensive, however, to route the callthrough local gateway 116. For example, a call that is routed through alocal gateway that is connected to the Class 5 of that same area code,the charges would likely be less. In other words, once the call begins,the media stream will be routed directly from the handset 112 to localgateway 116.

Emergency services, e.g., “911” calls, could be treated in the samemanner. When an emergency service is needed, the user would dial thestring “9-1-1.” A setup message would then be routed to the proxy server134, which would in turn cause the call to be routed to local gateway116. For the purpose of this invention, authentication at the proxy isan optional step. In other words, the proxy server 134 could examine thedialed string and determine that it is an emergency string and forgoauthentication. The PSTN 130, in areas that include 911 services, isadapted to specially route the call to the proper authorities so that aresponse can be made.

One goal of the preferred embodiment of the present invention is to makeemergency services as reliable as possible. There are a number of thingsthat could go wrong that would cause reliability issues. For example,the line 140 connecting the customer premise 110 to the service provider120 could fail in some cases, a business or community may have only onephysical line, e.g., a T1 data link or is or a fractional T3 link,leaving the premise. If this one line is damaged for any reason, the LAN114 will lose connectivity to IP network 126.

In another example, there may be problems with the service provider'snetwork. Preferably, the network 126 includes redundancy; it would notbe uncommon to have hundreds of different paths between elements. Inthis case, it would be unlikely that a router failure could causeconnectivity to be lost. In the case of a natural disaster or otherlarge-scale emergency, however, the network could become overwhelmed,with people trying to call into and out of the affected area. Therefore,it would be useful to have an alternate treatment of emergency servicescalls.

In a preferred embodiment, these problems are avoided by having thehandset 112 recognize an emergency services call and route that calldirectly to the PSTN 130 through the local gateway 116. No provisioningis performed at the proxy server 134. In this manner, reliance on theproxy server 134 (or similar domain name servers) is removed. The callcan be routed even if the IP network 126 is inaccessible.

If for some reason the local gateway is down, then the call can berouted through the IP network 126. For example, using network gateway128 as a connection point to the PSTN 130 could still complete the call.

Another problem exists in areas that do not have 911 services. In thoseplaces, the user would need to dial the necessary emergency telephonenumber or numbers to reach the police, fire department, ambulance orwhichever other service is necessary. In other words, people would needto learn at least one and maybe more telephone numbers. In an emergency,however, it may be difficult to remember these numbers or to look themup.

To solve this problem, the present invention includes an embodimentwhere the handset 112 (or the gateway 116) can receive a dialed stringof “9-1-1” and map that string into a valid emergency services telephonenumber for that particular area. With this feature, the user will bepresented with a scenario that appears the same as those locales thathave implemented 911 services.

FIG. 2 provides a block diagram of an exemplary handset 112 that couldbe used with the present invention. The handset 112 would include a userinterface so that the user could use the telephone. As with manytelephones, the user interface could include a speaker, a microphone, akeypad and a display. These user interface features are presented in thefigure by the blocks 150, 152, 154 and 156, respectively labeled keypad,codec, audio and display.

The handset 112 also includes a controller 158 that can perform, amongother things, a provisioning procedure. The controller 158 couples toeach of the other elements in the phone 112 to provide overall controlof the system.

The handset 112 also includes a memory 160 that may be adapted to storea table that includes an indication of an emergency services telephonecall and a destination address corresponding with the emergency servicestelephone call. In a preferred embodiment, the table also includes amapped string that provides the emergency services telephone number forthat particular locale. The memory 160 is preferably a non-volatilememory such as flash memory or a non-volatile RAM (e.g, DRAM or SRAMwith its own battery).

In the illustrated example, the table includes two entries. The firstentry is a dialed string “9-1-1.” In the United States this number isoften used for emergency services. Other countries may use other stringssuch as “0-0-0” in Australia or “1-1-0” or “1-1-2” in European Communitycountries. The table also stores the IP address corresponding to thelocal network gateway. In this case, the IP address is 124.23.2.1, whichis assumed to be the address of gateway 116. The third entry on this rowis the telephone number for local emergency services. In some cases,this could simply be “911.” In the illustrated example, however, theemergency services telephone number is “312-7888.” This telephone numberis typically a local seven-digit or ten-digit number.

In the case where the local emergency services number is not “911,” thetable also preferably includes an entry for the local emergency servicesnumber. This particular example, a dialed string of “3-1-2-7-8-8-8” willbe mapped into 312-7888 and routed to the local gateway 116, which is atIP address 124.23.2.1. For international compatibility, one emergencyservices number could be mapped into another. For example, a telephonebeing used in Germany where the emergency services number is “110” canhave a dialed string of “9-1-1” mapped into “110.”

While the emergency services calls are routed directed to the localgateway 116, all other calls can be routed to proxy server 134 (FIG. 1).In other embodiments, other calls, e.g., internal extensions, can alsobe routed without use of the proxy server 134.

FIG. 2 also shows a provisioning function 164 which can be performedfrom some device connected to LAN 114. The provisioning device 164 canbe used to set the values within the mapping table 160. In a typicalembodiment, the user of the telephone does not know the IP address ofthe local gateway (or likely even the existence of a local gateway).Rather, the system administrator is typically responsible formaintaining the table in memory 160. This maintenance can be performedremotely by use of provisioning device 164, a device which is located atthe local customer premise 110.

The present invention has thus far been discussed in the context ofemergency services. It should be understood, however, that theseconcepts could be applied to other circumstances where it is desirablefor a particular telephone call to be treated differently than othercalls. For example, a specific user could be given the option to maptelephone calls for specific uses, e.g., a family member, boss, orstockbroker.

One specific example of another use would be to report outages of thetelecommunications system. For example, if link 140 (FIG. 1) between thecustomer premise portion 110 and the service provider portion 120 is notfunctioning, then the customer could not use the system to notify theservice provider. In this case, the customer could use a special serviceprovider number (or use a specialized button or command on the handset)for service notification. This number could be cause the system tobypass the link 140 and route the call to the service provider throughgateway 116.

While this invention has been described with reference to illustrativeembodiments, this description is not intended to be construed in alimiting sense. Various modifications and combinations of theillustrative embodiments, as well as other embodiments of the invention,will be apparent to persons skilled in the art upon reference to thedescription. It is therefore intended that the appended claims encompassany such modifications or embodiments.

1. A method, comprising: receiving, at a telephony device, a callindication from a user; searching a memory of the telephony device foran entry corresponding to the call indication; routing a telephone callfrom the telephony device to a local gateway coupled to a first networkwithout first accessing a proxy server coupled to a second network whenit is determined that the memory includes an entry corresponding to thecall indication; and routing the telephone call from the telephonydevice to the proxy server without passing the telephone call throughthe local gateway when it is determined that the memory does not includean entry corresponding to the call indication.
 2. The method of claim 1,where the memory includes a listing of call indications that triggerrouting of the telephone call to the local gateway.
 3. The method ofclaim 2, where each call indication listing includes an internetprotocol (IP) address of the local gateway.
 4. The method of claim 2,where each call indication listing includes a mapped stringcorresponding to the call indication, where the information in themapped string is output by the local gateway in response to receipt ofthe corresponding call indication.
 5. The method of claim 4, where themapped string matches the call indication.
 6. The method of claim 4,where the call indication is a string received from the user and wherethe mapped string corresponding to the call indication does not matchthe received string.
 7. The method of claim 1, where the call indicationcorresponds to a button pressing on the telephony device.
 8. The methodof claim 1, where the call indication is an alphanumeric string receivedby the telephony device.
 9. The method of claim 8, where thealphanumeric string includes a telephone number.
 10. The method of claim9, where searching the memory for the entry corresponding to the callindication further comprises: searching a lookup table for a listingcorresponding to the received telephone number; and routing thetelephone call to the local gateway at an address included in thelisting.
 11. The method of claim 10, further comprising: translating thereceived telephone number into a mapped string included in the listingprior to routing the telephone call to the local gateway.
 12. The methodof claim 9, where the telephone number is an emergency servicestelephone number.
 13. A telecommunications device, comprising: aninterface to receive a call indication from a user; and a controller to:determine whether the call indication relates to a first type of call,route a telephone call directly to a local gateway upon determining thatthe call indication relates to the first type of call, and route thetelephone call to a proxy server and not to the local gateway, upondetermining that the call indication does not relate to the first typeof call.
 14. The device of claim 13, where the local gateway is coupledto a first network and the proxy server is coupled to the secondnetwork, where the first network is different from the second network.15. The device of claim 14, where the first network is a public switchedtelephone network and the second network is an Internet protocolnetwork.
 16. The device of claim 13, further comprising: a memory tostore a listing of call indications relating to the first type of call,where the controller is further to search the memory for a listingcorresponding to the received call indication.
 17. The device of claim16, where each call indication listing stored in the memory includes alocal gateway internet protocol (IP) address.
 18. The device of claim16, where each call indication listing stored in the memory includes amapped string output to the local gateway upon receipt of acorresponding call indication.
 19. A telephone system comprising: atleast one handset operatively coupled to a local area network; a localnetwork gateway operatively coupled to the local area network, the localnetwork gateway operatively coupled to a circuit-switched network; and aproxy server operatively coupled to the local area network, the proxyserver operatively coupled to an Internet protocol network, where thehandset routes a telephone call directly to the local network gatewaywithout passing the telephone call through the proxy server upon receiptof a first type of call indication from a user.
 20. The device of claim13, further comprising: an internet protocol (IP) interface; where thecontroller is further to: route, through the IP interface, the telephonecall directly to the local gateway upon determining that the callindication relates to the first type of call; and route, through the IPinterface, the telephone call to the proxy server, and not to the localgateway, upon determining that the call indication does not relate tothe first type of call.